import math
def circlearea(r):
    result = math.pi*r*r
    return result
r = 10
print('半径为',r,'的圆面积为：',circlearea(r))
#lambda表达式
import math
r = 10
result = lambda r:math.pi*r*r
print('半径为',r,'的圆面积为：',result(r))